Circuit breaker



Dec. 12, 1933.

E, D. ANGELL clnCUIT BREAKER Filed Feb Patented Dec. 12, 1933 i' UNITED STATES PATENT 1 oFFl-CEv 8 Claims.

This invention relates to circuit breakers and more especially to circuit breakers of the fuseplug type that may be used either to protect, or as a. substitute for, fuses, although it will be understood that my invention is capable of general application to open circuit when overload occurs.

The object of my invention is to improve and simplify the construction and augment the efciency of thermally-actuated circuit breakers in the manner hereinafter more fully set forth.

In the drawing which accompanies and forms a part of this specification- Figure 1 is a central section of a circuit breaker embodying my invention taken on the line 1-1 of Fig. 2; and

Fig. 2 is a central section taken on the line 22 of Fig, 1.

1in.V the particular drawing selected for more fully disclosing the principle underlying my invention and which is to be considered as illustrative merely and not as restrictive, 10 is a hollow plug of insulating material provided with external contacts, shown .in the present instance as the end contact 11 and the threaded shell 12, whereby the plug may be screwed into the usual socket to connect the saine to the circuit to be protected.

Enclosed within the shell are a pair of substantially parallel, oppositely-disposed conducting strips 13,14 and a pair of substantially parallel strips 15, 16 of any suitable thermostatic material, the latter being arranged at right angles to the former and each consisting of a plurality of materials having diierent degrees oi? expansion under the same temperature.

1n the present instance said strips are supported as follows: The end portion of each strip is bent at right ang/les to the vertical portion and perforated to receive the bolt 17, the upper portion of which is provided with an insulating sleeve 16. insulating washers 19 are interposed between the perforated bent portion of said strips in such manner as to insulate strip 13 from strip i4.- and to insulate the thermostatic strip 15 from the thermostatic strip 16. The strip 14 is in electrical contact with the thermostat strip 16 and the thermostat strip 15 is in electrical contact with a washer 20 which in turn is connected electrically to the threaded shell l2.

Contact members 21, 22 are connected to the upper ends of the thermostatic strips l5, 16, respectively, and engage a circuit-closing member 23, shown in the present instance as rigidly secured to the rod 24. Preferably each contact member has a bevelled face and the circuit-closing member has a surface bevelled reversely tothe faces of said contact members. The upper ends of the strips 13, 14 are in engagement with the circuit-closing member 25 rigidly connected 60 with the hollow push-plug 26. As shown in the present instance, the upper end portions of said strips 13, 14 are bent at right angles and engage the upper surface of the circuit-closing member 25.

By means of the spring 27 interposed between the head 28 of the rod 24 and the bottom of the hollow push-plug 26, the circuit-closing member 23 is maintained normally in electrical contact with the contact members 21, 22, and the spring 29 disposed in the socket 30 formed in theupper face of the plug and taking against'the flange 31 of the hollow push-plug'l serves to maintain the circuit-closing member 25 normally in electrical contact with the end portions 26 vof the conduct- 75 ing strips 13, 1li. Y

It will thus be seen that normally the manuallyoperable switch comprising the conducting strips 13, 14, the thermally-controlled switch comprising the thermcstatic elements 15, 1s and thc S@ tc the other terminal ci the circuit through the shell 12.

Immediately below the circuit-closing member 23 a body of non-arcing material 32, such as carbon, is attached to the rod 24 and'below said 9 carbon body a tapered plug 33 of insulating material is secured to said rod. In the present instance the non-arcing member is shown as a washer held in position by the insulating plug which may be threaded to said rod.

The operation is as follows: On overload the thermostatic strips become heated and bend outwardly permitting the spring 27 to raise the rod 24 and thereby draw the circuit-closing member out of co-operative position with respect to the contact members 21, 22, theinsulating plug 23 now intervening between said contact members, with the result that as soon as the thermostatic strips become cooled and swing toward each other, they will rest against said insulating plug,

thereby maintaining the circuit open until the device is re-set. I prefer to bevelthe lower surfaces of the contact 'members 21, 22 and to give the upper face of the circuit ,closer 23 a corresponding bevel in the reverse direction'to minimize the friction. that would otherwise exist and make the circuit breaker more sensitive and reliable. The washer of carbonor other non-arcing material, although not essential, is highly desirable to minimize arcing when the circuit closer 23 is drawn out of electrical contact with the members 21, 22. To re-set the circuit breaker the hollow pushplug is depressed, whereupon the manually-operablel switch' ,comprised of the strips 13, 14 and circuit closer 25 is opened and then the circuit- `closer 23 is brought into electrical contact with the members 21, 22, the rod 24 being forced downwardly by the engagement ,of the head 28 thereof with the closure, (preferably transparent) of the hollow push-plug 26 and, iinally,'as the hollow push-plug is released, the retrograde movement vthereof elected by the spring 29 will close the manually-operable'switch. If the overload or short-circuit difficulty has not been rectifled, the thermostatic elements immediately will become heated again and the thermally-controlled switch, of which they form a part, will open the circuit. It will thus be seenl that it will be impossible to maintain the circuit in closed condition by holding the push-rod 3l down.

When the thermally-controlled switch is open the contact members 21, 22 will be in engagement with the tapered end of the plug 33 and such taper, although not essential is desirable to minimize the friction that would otherwise exist between said contact members and insulating plug upon the downward movement of the rod 24.

Having thus disclosed an illustrative embodi` ment of my invention, without however limiting myself thereto, what I claim and desire to secure by Letters Patent is: Y 1. A circuit breaker comprising in combination a pair of oppositely-disposed thermostatic elements, means arranged for electrically connecting said elements in an electric circuit, contact members connected, respectively, to said thermostatic elements, each said contact member having a bevelled face, a movable circuit-closing member having a surface bevelled reversely to the bevelled faces of said contact members, resilient means holding said contact members and circuit-closing member in circuit-closing position with the bevelled surface of said circuit-closing member in electrical contact with the bevelled faces of said contact members, an insulating member Aconnected for movement with said circuit-closing memberv and disposed `to intervene between said contact members when-said circuit-closing member is moved by said resilient means out of circuit-closing position and manually-actuated means for restoring said circuit-closing member to circuit-closing position.

2. A circuit breaker comprising in combination a housing having external contacts and enclosing a thermally-controlled switch said switch comprising bimetallic strips, each consisting of a plurality of materials having different degrees of expansion under the same temperature, a man- 'ually-operable switch means maintaining said manually-operable switch normally closed irrespective of the condition of said thermally-controlled switch, meanselectrically connecting said contacts and said switches. resilient means mainmaintainingv said `manually-operable extending into said housing and carrying one, member of said manually-operable switch, resilient means co-operating with said push-plug for switch closed, a rodcarrying one member of said therlmany-controlled switch, the` outer end' of said rod -being disposedwithin said hollow push-plug,- and resilient means co-operating with said rod for maintaining said thermally-controlled switch closed, said rod and hollow push-plug being disposed in a manner successively to open said manually-operable switch and close said thermal1y. controlled switch when' movedtogether into said housing. r

4. A circuit breaker comprising in combination a housing having external contacts and enclosing a thermally-controlled switch, said switch comprising a pair of oppositely-disposed thermo-l static elements and each of said elements comprising a bimetallic strip formed of a plurality of materials having different degrees oi' expansion under the same temperature, contact members connected, respectively, to said thermostatic elements, a push-rod extending into said housing, a circuit-closing member carried by Said push-rod and disposed for co-operation with said contact members, and aninsulating member also carried by said push-rod and arranged to intervene between said contact members when said l circuit-closing member is in circuit-opening position, the outer end of 'said insulating member being tapered to permit the passage thereof between said contact members on the inward movement of said push-rod.

5. A circuit breaker comprising in combination a-housing having external contacts and enclosing a thermally-closed switch and a manually-operated vswitch electrically connected with said thermally-controlled switch and said contacts,'said thermally-controlled switch .comprising two oppositely-dispose'd substantially-parallel strips of thermostatic material and said manually-operated switch comprising two oppositely-disposed substantially-parallel strips of conducting material arranged in a plane substantially at right angles to the plane of said strips of thermo-- static material, a circuit-closing member disposed to co-operate with said strips of thermostatic material, a circuit-closing member disposed to cooperate with said strips of conducting material, means for moving the last-mentioned circuitclsing member out of contact with said strips of conducting material, and means controlled by said means for moving the first-mentioned circuit-closing member into co-operation with said strips of thermostatic material.

6. A 'circuit breaker comprising in combination a manually-operable switch, a thermally-controlled switch, said thermally-controlled switch comprising bimetallic strips, each consisting of a plurality of materials having different degrees of expansion under the same temperature, means connecting said switches electrically, `means maintaining said manually-operable switch normallyclosedirrespectiveoi'the condition ofsaid thermally-controlled switch. manually-actuated means for opening said manually-Operable s switch, and means controlled by said manuallyactuated means for closing said thermally-controlled switch.

7. Acircuit breaker comprising in combination a manually-operable a thermally-controlied switch, said thermally-controlled switch comprising bimetallic strips each consisting of a plurality of materials having different degrees o! expansion under the-same temperature, means connecting said switches electrically. means maintaining said manually-operable switch normallyclosedirrespectiveoftheccnditionoi said thermally-controlled switch, manually-actuated position.

ELVIN D. ANGELI. 

